1. Field of the Invention
The present invention relates to a location acquisition and location-based service (LBS) system, and particularly, to a universal location identifier (ULID) data structure, a ULID-based location acquisition method and an LBS system, in which user location information is checked using radio frequency identification (RFID) tags attached to various buildings, stores and road signs as well as ULID received from the RFID tags, and various LBSs are provided based on the location information.
2. Description of the Related Art
Today, with the advance of wireless communication technology such as mobile communication, the LBS is expected to create a huge market in the field of wireless Internet services in the future. The LBS combines location information of a moving user or vehicle with other various information in real time and provides an additional application service necessary for the user. Location acquisition is one of the most important factors in providing the user with the LBS service.
The location information is the contents of the location of an object and the real geographical feature on the ground, which are represented using a predetermined method such as a global positioning system (GPS) in general. The GPS is an electromagnetic wave navigation system that precisely measures 3D location, speed and time of an object on the ground using satellites, which receives a satellite signal transmitted from a satellite identifying the location of the object by triangulation, measures the elapsed time of the electromagnetic wave to arrive at the system and calculates the user location. Recently, the communication systems such as CDMA and GSM employ a network system that provides location information of a mobile terminal by using the precise location of a wireless relay (or a base station). It is advantageous that the location information can be transferred to a user in a building.
FIG. 1 illustrates a typical example in which location of a hand-held telephone is acquired and the LBS is provided using the conventional mobile communication described above.
Referring to FIG. 1, a hand-held telephone 11 of a mobile communication company keeps connecting to a base station 15 for communication. The locations of the hand-held telephones connected to each base station 15 are managed by the mobile communication company. The company can provide the LBS of cell-ID level by using the location information. To acquire the more precise location information, triangulation is performed through a positioning determination entity (PDE) 12 by using signals transmitted from more than two base stations 15. The location of the hand-held telephone with a GPS module can be acquired using a signal received by a GPS satellite 16 as well as a base station signal. In some cases, the location information can be calculated by a mixed method with the base station signal. The acquired location information is transferred to an internal or external CP LBS server 14 through a location information gateway 13 of a mobile communication company. The LBS server 14 combines the acquired location information with map and directory information to provide a service through wireless Internet and wire Internet.
However, when the location information obtained using a GPS is provided to a civilian user, an error can be embedded into the location information on purpose for security. Also, the precision of the location information may deteriorate due to geographical displacement of a satellite that transmits a signal or the satellite may transmit erroneous location information due to an electromagnetic wave interface problem. The precision of the location information provided using a network system is low since it is different from a relay in their time and electromagnetic wave signals. Also, the precision may vary very much according to the location of a user. In the technologies, it is dangerous that private location information may leak through a server when the server performs a location information process to estimate location since a hand-held terminal is short of computing power as an assisted GPS.
Therefore, the technology is required, in which precise location information is extracted in a city and an interior to provide a service without any leakage of private location information.
In the present invention, an LBS is provided using an RFID so as to intend to solve the above-mentioned problem of the related arts. The basic structure of an RFID will be described in brief.
Recently, an RFID technology is applied to various industries such as electronics, dresses and foods. The RFID consisting of a miniaturized IC chip and an antenna in the fields can work as a wireless tag that can obtains the information on goods without direct contact. For this reason, the RFID is expected to substitute for the conventional optical barcode that obtains information through contact.
FIG. 2 is a block diagram of a basic structure of a system using the RFID and an RFID reader.
The RFID system is a wireless communication system consisting of an RFID reader 20 for reading and interpreting information and an RFID transponder 30 for providing the corresponding information. The RFID transponder 30 is called an RFID tag.
As widely known, the RFID systems are classified into an inductively coupled system and an electromagnetic wave system according to their connection for mutual communication, and are also classified into an active RFID and a passive RFID according to whether the RFID tag uses an additional energy source such as a battery or an external power source or not for its operation.
Most of the inductively coupled RFID tags are always operated as the passive RFID system. In other words, the IC chip in the RFID tag obtains all the energy for its operation from a reader and does not necessitate any additional power source. For this purpose, an antenna coil 25 of the RFID reader 20 generates strong electromagnetic field of high frequency around the antenna coil 25. Some of the emitted electromagnetic field generates inductive voltage in a coil antenna of a tag spaced from the RFID reader 20 to provide the tag with energy. For this reason, the passive RFID can be used semi-permanently and is small-sized but has a short transmission range. Since the active tag uses an additional energy source, a strong response signal is generated and transmitted so that the RFID signal can be detected at a long range even in the region in which transmission signal of the reader is weak. However, since the battery has a comparatively short life span, the effective life span of the tag is limited and is large-sized and expensive compared with the passive tag.
FIG. 3 illustrates a general configuration of the passive RFID. The passive RFID 30 includes an IC 31 and a coil antenna 32 in general. A capacitor 33 is selectively used to synchronize an operation frequency of the tag to a predetermined value. The IC 31 permanently stores a tag identifier and other useful information, interprets and processes a command received from the RFID reader 20, responds to the RFID reader 20, and includes software and a circuit for solve a collision caused when a multiplicity of tags assists hardware to responds to inquiry at one time. The location and characteristic of the antenna 32 are different according to the required operation frequency for an RFID portion of a tag. For example, the RFID tag of a frequency such as 2.4 GHz includes a linear dipole antenna or a folded dipole antenna while the RFID tag of a frequency such as 13.56 GHz includes a spiral antenna or a coil antenna.
The RFID includes information that can be used as an identifier in a memory 34 of the IC chip. FIG. 4A illustrates a basic structure of 96-bit electronic product code (EPC) suggested by the MIT AutoID center and its embodiment. In other words, the EPC consists of a header, an EPC manager, an object class and a serial number part.
The header identifies its version. The EPC manager is an identifier of a manufacturer that can allocate the EPC. The object class is used to specify a category such as goods that the manufacturer produces. The serial number part identifies a serial number of the goods.
FIG. 4B illustrates a structure of a location code suggested by AutoID center in the year of 2000. In the present invention, the location code is used as a reference code. The code includes an 8-bit header for identifying its version and 32-bit parts for identifying latitude, longitude and altitude respectively.
MIT AutoID center has suggested the types of the EPC code as shown in FIG. 4C but has not suggested a service method using the types of the EPC code.